HTML

radio button multiple selection with same name

You can't. 
Radio buttons are there for a single choice. 
For multiple choices, you need checkboxes.

allow multiple select on radio button in html

<fieldset>
    <legend>Please select one of the following</legend>
    <input type="radio" name="action" id="track" value="track" /><label for="track">Track Submission</label><br />
    <input type="radio" name="action" id="event" value="event"  /><label for="event">Events and Artist booking</label><br />
    <input type="radio" name="action" id="message" value="message" /><label for="message">Message us</label><br />
</fieldset>

why am i able to select multiple radio buttons

Solution is to give them the same NAME